Research in this laboratory will continue to focus on the two peptides isolated and chemically characterized in this laboratory, substance P, arg-pro-lys-pro-gln-gln-phe-phe-gly-;eu-met-NH2, and neurotensin, (glu-leu-tyr-glu-asn-lys-pro-arg-arg-pro-tyr-ile-leu-OH. Because of evidence suggesting an important role for substance P in mediating sensory transmission, a collaborative study was undertaken with Dr. Gerald Fischbach's laboratoty on the presence and the regulation of release of immunoreactive substance P in dispersed cell cultures of sensory neurons from chick dorsal root ganglia. Neurons in these cultures release both immunoreactive substance P and somatostatin in response to depolarization with high K ion in a calcium dependent manner. Addition of enkephalin can inhibit the K ion induced release of immunoreactive substance P. These studies will be extended to examine the effect of addition of GABA, serotonin, and norepinephrine on this response. Studies will be contined on the measurement of SP, NT, LHRH, and SRIF in cultures of hypothalamic tissue taken from fetal and newborn rats. The size and density of rat brain synaptic vesicles containing substance P and neurotensin will be studied by chromatography on controlled pore glass beads and by velocity and equilibrium sedimentation on sucrose gradients in parallel with determinations of monamine-containing vesicle size and density. A series of experiments has been initiated to determine whether SP plays a role in regulating the release of LHRH or its activity in stimulating FSH and LH release from the anterior pituitary gland.